* [PATCH 5.10.y 1/2] ext4: introduce ITAIL helper
2025-12-16 8:19 [PATCH 5.10.y 0/2] Backport 2 commits to fix a KASAN ext4 splat David Nyström
@ 2025-12-16 8:19 ` David Nyström
2025-12-16 8:19 ` [PATCH 5.10.y 2/2] ext4: fix out-of-bound read in ext4_xattr_inode_dec_ref_all() David Nyström
1 sibling, 0 replies; 3+ messages in thread
From: David Nyström @ 2025-12-16 8:19 UTC (permalink / raw)
To: stable; +Cc: Theodore Ts'o, Ye Bin, Sasha Levin, David Nyström,
Jan Kara
From: Ye Bin <yebin10@huawei.com>
Introduce ITAIL helper to get the bound of xattr in inode.
Signed-off-by: Ye Bin <yebin10@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://patch.msgid.link/20250208063141.1539283-2-yebin@huaweicloud.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
(cherry picked from commit 69f3a3039b0d0003de008659cafd5a1eaaa0a7a4)
Signed-off-by: David Nyström <david.nystrom@est.tech>
---
fs/ext4/xattr.c | 10 +++++-----
fs/ext4/xattr.h | 3 +++
2 files changed, 8 insertions(+), 5 deletions(-)
diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c
index fa8ce1c66d12..73a9b2934865 100644
--- a/fs/ext4/xattr.c
+++ b/fs/ext4/xattr.c
@@ -599,7 +599,7 @@ ext4_xattr_ibody_get(struct inode *inode, int name_index, const char *name,
return error;
raw_inode = ext4_raw_inode(&iloc);
header = IHDR(inode, raw_inode);
- end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
+ end = ITAIL(inode, raw_inode);
error = xattr_check_inode(inode, header, end);
if (error)
goto cleanup;
@@ -744,7 +744,7 @@ ext4_xattr_ibody_list(struct dentry *dentry, char *buffer, size_t buffer_size)
return error;
raw_inode = ext4_raw_inode(&iloc);
header = IHDR(inode, raw_inode);
- end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
+ end = ITAIL(inode, raw_inode);
error = xattr_check_inode(inode, header, end);
if (error)
goto cleanup;
@@ -826,7 +826,7 @@ int ext4_get_inode_usage(struct inode *inode, qsize_t *usage)
goto out;
raw_inode = ext4_raw_inode(&iloc);
header = IHDR(inode, raw_inode);
- end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
+ end = ITAIL(inode, raw_inode);
ret = xattr_check_inode(inode, header, end);
if (ret)
goto out;
@@ -2215,7 +2215,7 @@ int ext4_xattr_ibody_find(struct inode *inode, struct ext4_xattr_info *i,
header = IHDR(inode, raw_inode);
is->s.base = is->s.first = IFIRST(header);
is->s.here = is->s.first;
- is->s.end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
+ is->s.end = ITAIL(inode, raw_inode);
if (ext4_test_inode_state(inode, EXT4_STATE_XATTR)) {
error = xattr_check_inode(inode, header, is->s.end);
if (error)
@@ -2739,7 +2739,7 @@ int ext4_expand_extra_isize_ea(struct inode *inode, int new_extra_isize,
*/
base = IFIRST(header);
- end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
+ end = ITAIL(inode, raw_inode);
min_offs = end - base;
total_ino = sizeof(struct ext4_xattr_ibody_header) + sizeof(u32);
diff --git a/fs/ext4/xattr.h b/fs/ext4/xattr.h
index e5e36bd11f05..9a596e19c2b1 100644
--- a/fs/ext4/xattr.h
+++ b/fs/ext4/xattr.h
@@ -68,6 +68,9 @@ struct ext4_xattr_entry {
((void *)raw_inode + \
EXT4_GOOD_OLD_INODE_SIZE + \
EXT4_I(inode)->i_extra_isize))
+#define ITAIL(inode, raw_inode) \
+ ((void *)(raw_inode) + \
+ EXT4_SB((inode)->i_sb)->s_inode_size)
#define IFIRST(hdr) ((struct ext4_xattr_entry *)((hdr)+1))
/*
--
2.48.1
^ permalink raw reply related [flat|nested] 3+ messages in thread* [PATCH 5.10.y 2/2] ext4: fix out-of-bound read in ext4_xattr_inode_dec_ref_all()
2025-12-16 8:19 [PATCH 5.10.y 0/2] Backport 2 commits to fix a KASAN ext4 splat David Nyström
2025-12-16 8:19 ` [PATCH 5.10.y 1/2] ext4: introduce ITAIL helper David Nyström
@ 2025-12-16 8:19 ` David Nyström
1 sibling, 0 replies; 3+ messages in thread
From: David Nyström @ 2025-12-16 8:19 UTC (permalink / raw)
To: stable; +Cc: Theodore Ts'o, Ye Bin, Sasha Levin, David Nyström,
Jan Kara
From: Ye Bin <yebin10@huawei.com>
There's issue as follows:
BUG: KASAN: use-after-free in ext4_xattr_inode_dec_ref_all+0x6ff/0x790
Read of size 4 at addr ffff88807b003000 by task syz-executor.0/15172
CPU: 3 PID: 15172 Comm: syz-executor.0
Call Trace:
__dump_stack lib/dump_stack.c:82 [inline]
dump_stack+0xbe/0xfd lib/dump_stack.c:123
print_address_description.constprop.0+0x1e/0x280 mm/kasan/report.c:400
__kasan_report.cold+0x6c/0x84 mm/kasan/report.c:560
kasan_report+0x3a/0x50 mm/kasan/report.c:585
ext4_xattr_inode_dec_ref_all+0x6ff/0x790 fs/ext4/xattr.c:1137
ext4_xattr_delete_inode+0x4c7/0xda0 fs/ext4/xattr.c:2896
ext4_evict_inode+0xb3b/0x1670 fs/ext4/inode.c:323
evict+0x39f/0x880 fs/inode.c:622
iput_final fs/inode.c:1746 [inline]
iput fs/inode.c:1772 [inline]
iput+0x525/0x6c0 fs/inode.c:1758
ext4_orphan_cleanup fs/ext4/super.c:3298 [inline]
ext4_fill_super+0x8c57/0xba40 fs/ext4/super.c:5300
mount_bdev+0x355/0x410 fs/super.c:1446
legacy_get_tree+0xfe/0x220 fs/fs_context.c:611
vfs_get_tree+0x8d/0x2f0 fs/super.c:1576
do_new_mount fs/namespace.c:2983 [inline]
path_mount+0x119a/0x1ad0 fs/namespace.c:3316
do_mount+0xfc/0x110 fs/namespace.c:3329
__do_sys_mount fs/namespace.c:3540 [inline]
__se_sys_mount+0x219/0x2e0 fs/namespace.c:3514
do_syscall_64+0x33/0x40 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x67/0xd1
Memory state around the buggy address:
ffff88807b002f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffff88807b002f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88807b003000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
^
ffff88807b003080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ffff88807b003100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
Above issue happens as ext4_xattr_delete_inode() isn't check xattr
is valid if xattr is in inode.
To solve above issue call xattr_check_inode() check if xattr if valid
in inode. In fact, we can directly verify in ext4_iget_extra_inode(),
so that there is no divergent verification.
Fixes: e50e5129f384 ("ext4: xattr-in-inode support")
Signed-off-by: Ye Bin <yebin10@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://patch.msgid.link/20250208063141.1539283-3-yebin@huaweicloud.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
(cherry picked from commit 5701875f9609b000d91351eaa6bfd97fe2f157f4)
Signed-off-by: David Nyström <david.nystrom@est.tech>
---
fs/ext4/inode.c | 5 +++++
fs/ext4/xattr.c | 26 +-------------------------
fs/ext4/xattr.h | 7 +++++++
3 files changed, 13 insertions(+), 25 deletions(-)
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 97f7cac0d349..719d9a2bc5a7 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -4650,6 +4650,11 @@ static inline int ext4_iget_extra_inode(struct inode *inode,
*magic == cpu_to_le32(EXT4_XATTR_MAGIC)) {
int err;
+ err = xattr_check_inode(inode, IHDR(inode, raw_inode),
+ ITAIL(inode, raw_inode));
+ if (err)
+ return err;
+
ext4_set_inode_state(inode, EXT4_STATE_XATTR);
err = ext4_find_inline_data_nolock(inode);
if (!err && ext4_has_inline_data(inode))
diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c
index 73a9b2934865..16b9c87fd3d8 100644
--- a/fs/ext4/xattr.c
+++ b/fs/ext4/xattr.c
@@ -263,7 +263,7 @@ __ext4_xattr_check_block(struct inode *inode, struct buffer_head *bh,
__ext4_xattr_check_block((inode), (bh), __func__, __LINE__)
-static int
+int
__xattr_check_inode(struct inode *inode, struct ext4_xattr_ibody_header *header,
void *end, const char *function, unsigned int line)
{
@@ -280,9 +280,6 @@ __xattr_check_inode(struct inode *inode, struct ext4_xattr_ibody_header *header,
return error;
}
-#define xattr_check_inode(inode, header, end) \
- __xattr_check_inode((inode), (header), (end), __func__, __LINE__)
-
static int
xattr_find_entry(struct inode *inode, struct ext4_xattr_entry **pentry,
void *end, int name_index, const char *name, int sorted)
@@ -600,9 +597,6 @@ ext4_xattr_ibody_get(struct inode *inode, int name_index, const char *name,
raw_inode = ext4_raw_inode(&iloc);
header = IHDR(inode, raw_inode);
end = ITAIL(inode, raw_inode);
- error = xattr_check_inode(inode, header, end);
- if (error)
- goto cleanup;
entry = IFIRST(header);
error = xattr_find_entry(inode, &entry, end, name_index, name, 0);
if (error)
@@ -734,7 +728,6 @@ ext4_xattr_ibody_list(struct dentry *dentry, char *buffer, size_t buffer_size)
struct ext4_xattr_ibody_header *header;
struct ext4_inode *raw_inode;
struct ext4_iloc iloc;
- void *end;
int error;
if (!ext4_test_inode_state(inode, EXT4_STATE_XATTR))
@@ -744,14 +737,9 @@ ext4_xattr_ibody_list(struct dentry *dentry, char *buffer, size_t buffer_size)
return error;
raw_inode = ext4_raw_inode(&iloc);
header = IHDR(inode, raw_inode);
- end = ITAIL(inode, raw_inode);
- error = xattr_check_inode(inode, header, end);
- if (error)
- goto cleanup;
error = ext4_xattr_list_entries(dentry, IFIRST(header),
buffer, buffer_size);
-cleanup:
brelse(iloc.bh);
return error;
}
@@ -815,7 +803,6 @@ int ext4_get_inode_usage(struct inode *inode, qsize_t *usage)
struct ext4_xattr_ibody_header *header;
struct ext4_xattr_entry *entry;
qsize_t ea_inode_refs = 0;
- void *end;
int ret;
lockdep_assert_held_read(&EXT4_I(inode)->xattr_sem);
@@ -826,10 +813,6 @@ int ext4_get_inode_usage(struct inode *inode, qsize_t *usage)
goto out;
raw_inode = ext4_raw_inode(&iloc);
header = IHDR(inode, raw_inode);
- end = ITAIL(inode, raw_inode);
- ret = xattr_check_inode(inode, header, end);
- if (ret)
- goto out;
for (entry = IFIRST(header); !IS_LAST_ENTRY(entry);
entry = EXT4_XATTR_NEXT(entry))
@@ -2217,9 +2200,6 @@ int ext4_xattr_ibody_find(struct inode *inode, struct ext4_xattr_info *i,
is->s.here = is->s.first;
is->s.end = ITAIL(inode, raw_inode);
if (ext4_test_inode_state(inode, EXT4_STATE_XATTR)) {
- error = xattr_check_inode(inode, header, is->s.end);
- if (error)
- return error;
/* Find the named attribute. */
error = xattr_find_entry(inode, &is->s.here, is->s.end,
i->name_index, i->name, 0);
@@ -2743,10 +2723,6 @@ int ext4_expand_extra_isize_ea(struct inode *inode, int new_extra_isize,
min_offs = end - base;
total_ino = sizeof(struct ext4_xattr_ibody_header) + sizeof(u32);
- error = xattr_check_inode(inode, header, end);
- if (error)
- goto cleanup;
-
ifree = ext4_xattr_free_space(base, &min_offs, base, &total_ino);
if (ifree >= isize_diff)
goto shift;
diff --git a/fs/ext4/xattr.h b/fs/ext4/xattr.h
index 9a596e19c2b1..cbf235422aec 100644
--- a/fs/ext4/xattr.h
+++ b/fs/ext4/xattr.h
@@ -210,6 +210,13 @@ extern int ext4_xattr_ibody_set(handle_t *handle, struct inode *inode,
extern struct mb_cache *ext4_xattr_create_cache(void);
extern void ext4_xattr_destroy_cache(struct mb_cache *);
+extern int
+__xattr_check_inode(struct inode *inode, struct ext4_xattr_ibody_header *header,
+ void *end, const char *function, unsigned int line);
+
+#define xattr_check_inode(inode, header, end) \
+ __xattr_check_inode((inode), (header), (end), __func__, __LINE__)
+
#ifdef CONFIG_EXT4_FS_SECURITY
extern int ext4_init_security(handle_t *handle, struct inode *inode,
struct inode *dir, const struct qstr *qstr);
--
2.48.1
^ permalink raw reply related [flat|nested] 3+ messages in thread